The present invention relates to a vehicle drive device which includes a hydraulically operated speed change mechanism, is connected to an engine for use, and includes an electric pump that generates a hydraulic pressure to be supplied to the speed change mechanism.
In recent years, an increasing number of vehicles have an idling stop function to stop an engine when the vehicle is stopped, in order to reduce fuel consumption and exhaust emission. Moreover, hybrid vehicles having an engine and a rotating electrical machine as a driving force source generally have a function to stop the engine when the vehicle is stopped or when the vehicle is decelerated. In vehicles including a hydraulically operated speed change mechanism, however, a mechanical pump, which is driven by an engine, is stopped when the engine is stopped. As a result, no hydraulic pressure is supplied to the speed change mechanism, whereby the speed change mechanism cannot be operated properly. Thus, a mechanism has been known in which an electric pump is provided as an auxiliary pump in addition to the mechanical pump so that a hydraulic pressure generated by the electric pump is supplied to the speed change mechanism when the engine is stopped.
It is usually difficult to dispose such an electric pump inside a vehicle drive device. Thus, the electric pump is often mounted in contact with the exterior of a case of the vehicle drive device. In the case where the electric pump is mounted on the exterior of the case, a structure in which the electric pump is mounted on a side surface of a torque converter housing of the vehicle drive device (see, for example, Japanese Patent Application Publication No. JP-A-2002-054724 (FIGS. 2 and 3)) has already known in the art. Moreover, a structure in which the electric pump is mounted on a lower surface of the torque converter housing of the vehicle drive device (see, for example, United States Patent Application Publication No. 2005/0205382 (FIGS. 1 and 3)) has also been known in the art.